Single.CompareTo Method (Single)

.NET Framework 4.6 and 4.5

Compares this instance to a specified single-precision floating-point number and returns an integer that indicates whether the value of this instance is less than, equal to, or greater than the value of the specified single-precision floating-point number.

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)

Syntax

```public int CompareTo(
float value
)
```

Parameters

value
Type: System.Single

A single-precision floating-point number to compare.

Return Value

Type: System.Int32
A signed number indicating the relative values of this instance and value.

Return Value

Description

Less than zero

This instance is less than value.

-or-

This instance is not a number (NaN) and value is a number.

Zero

This instance is equal to value.

-or-

Both this instance and value are not a number (NaN), PositiveInfinity, or NegativeInfinity.

Greater than zero

This instance is greater than value.

-or-

This instance is a number and value is not a number (NaN).

Implements

IComparable<T>.CompareTo(T)

Remarks

Values must be identical to be considered equal. It is common for floating-point values to lose precision and to become nearly identical except for their least significant digits, especially when the values depend on multiple mathematical operations. Because of this, the return value of the CompareTo method at times may seem surprising. For example, multiplication by any value followed by division by the same value should produce the original value. However, in the following example, the computed value turns out to be greater than the original value. Showing all significant digits of the two values by using the "R" standard numeric format string indicates that the computed value differs from the original value in its least significant digits. For information about handling such comparisons, see the Remarks section of the Equals(Single) method.

```using System;

public class Example
{
public static void Main()
{
float value1 = 16.5457f;
float operand = 3.8899982f;
float value2 = value1 * operand / operand;
Console.WriteLine("Comparing {0} and {1}: {2}\n",
value1, value2, value1.CompareTo(value2));
Console.WriteLine("Comparing {0:R} and {1:R}: {2}",
value1, value2, value1.CompareTo(value2));
}
}
// The example displays the following output:
//       Comparing 16.5457 and 16.5457: -1
//
//       Comparing 16.5457 and 16.545702: -1
```

This method implements the System.IComparable<T> interface and performs slightly better than the Single.CompareTo method because it does not have to convert the value parameter to an object.

Note that, although an object whose value is NaN is not considered equal to another object whose value is NaN (even itself), the IComparable<T> interface requires that A.CompareTo(A) return zero.

Widening Conversions

Depending on your programming language, it might be possible to code a CompareTo method where the parameter type has fewer bits (is narrower) than the instance type. This is possible because some programming languages perform an implicit widening conversion that represents the parameter as a type with as many bits as the instance.

For example, suppose the instance type is Single and the parameter type is Int32. The Microsoft C# compiler generates instructions to represent the value of the parameter as a Single object, then generates a Single.CompareTo(Single) method that compares the values of the instance and the widened representation of the parameter.

Consult your programming language's documentation to determine if its compiler performs implicit widening conversions of numeric types. For more information, see the Type Conversion Tables in the .NET Framework topic.

Precision in Comparisons

The precision of floating-point numbers beyond the documented precision is specific to the implementation and version of the .NET Framework. Consequently, a comparison of two particular numbers might change between versions of the .NET Framework because the precision of the numbers' internal representation might change.

Examples

The following code example demonstrates generic and nongeneric versions of the CompareTo method for several value and reference types.

```// This example demonstrates the generic and non-generic versions of the
// CompareTo method for several base types.
// The non-generic version takes a parameter of type Object, while the generic
// version takes a type-specific parameter, such as Boolean, Int32, or Double.

using System;

class Sample
{
public static void Main()
{
string    nl = Environment.NewLine;
string    msg = "{0}The following is the result of using the generic and non-generic{0}" +
"versions of the CompareTo method for several base types:{0}";

DateTime  now = DateTime.Now;
// Time span = 11 days, 22 hours, 33 minutes, 44 seconds
TimeSpan  tsX = new TimeSpan(11, 22, 33, 44);
// Version = 1.2.333.4
Version   versX = new Version("1.2.333.4");
// Guid = CA761232-ED42-11CE-BACD-00AA0057B223
Guid      guidX = new Guid("{CA761232-ED42-11CE-BACD-00AA0057B223}");

Boolean  a1 = true,  a2 = true;
Byte     b1 = 1,     b2 = 1;
Int16    c1 = -2,    c2 = 2;
Int32    d1 = 3,     d2 = 3;
Int64    e1 = 4,     e2 = -4;
Decimal  f1 = -5.5m, f2 = 5.5m;
Single   g1 = 6.6f,  g2 = 6.6f;
Double   h1 = 7.7d,  h2 = -7.7d;
Char     i1 = 'A',   i2 = 'A';
String   j1 = "abc", j2 = "abc";
DateTime k1 = now,   k2 = now;
TimeSpan l1 = tsX,   l2 = tsX;
Version  m1 = versX, m2 = new Version("2.0");
Guid     n1 = guidX, n2 = guidX;

// The following types are not CLS-compliant.
SByte    w1 = 8,     w2 = 8;
UInt16   x1 = 9,     x2 = 9;
UInt32   y1 = 10,    y2 = 10;
UInt64   z1 = 11,    z2 = 11;
//
Console.WriteLine(msg, nl);
try
{
// The second and third Show method call parameters are automatically boxed because
// the second and third Show method declaration arguments expect type Object.

Show("Boolean:  ", a1, a2, a1.CompareTo(a2), a1.CompareTo((Object)a2));
Show("Byte:     ", b1, b2, b1.CompareTo(b2), b1.CompareTo((Object)b2));
Show("Int16:    ", c1, c2, c1.CompareTo(c2), c1.CompareTo((Object)c2));
Show("Int32:    ", d1, d2, d1.CompareTo(d2), d1.CompareTo((Object)d2));
Show("Int64:    ", e1, e2, e1.CompareTo(e2), e1.CompareTo((Object)e2));
Show("Decimal:  ", f1, f2, f1.CompareTo(f2), f1.CompareTo((Object)f2));
Show("Single:   ", g1, g2, g1.CompareTo(g2), g1.CompareTo((Object)g2));
Show("Double:   ", h1, h2, h1.CompareTo(h2), h1.CompareTo((Object)h2));
Show("Char:     ", i1, i2, i1.CompareTo(i2), i1.CompareTo((Object)i2));
Show("String:   ", j1, j2, j1.CompareTo(j2), j1.CompareTo((Object)j2));
Show("DateTime: ", k1, k2, k1.CompareTo(k2), k1.CompareTo((Object)k2));
Show("TimeSpan: ", l1, l2, l1.CompareTo(l2), l1.CompareTo((Object)l2));
Show("Version:  ", m1, m2, m1.CompareTo(m2), m1.CompareTo((Object)m2));
Show("Guid:     ", n1, n2, n1.CompareTo(n2), n1.CompareTo((Object)n2));
//
Console.WriteLine("{0}The following types are not CLS-compliant:", nl);
Show("SByte:    ", w1, w2, w1.CompareTo(w2), w1.CompareTo((Object)w2));
Show("UInt16:   ", x1, x2, x1.CompareTo(x2), x1.CompareTo((Object)x2));
Show("UInt32:   ", y1, y2, y1.CompareTo(y2), y1.CompareTo((Object)y2));
Show("UInt64:   ", z1, z2, z1.CompareTo(z2), z1.CompareTo((Object)z2));
}
catch (Exception e)
{
Console.WriteLine(e);
}
}

public static void Show(string caption, Object var1, Object var2,
int resultGeneric, int resultNonGeneric)
{
string relation;

Console.Write(caption);
if (resultGeneric == resultNonGeneric)
{
if      (resultGeneric < 0) relation = "less than";
else if (resultGeneric > 0) relation = "greater than";
else                        relation = "equal to";
Console.WriteLine("{0} is {1} {2}", var1, relation, var2);
}

// The following condition will never occur because the generic and non-generic
// CompareTo methods are equivalent.

else
{
Console.WriteLine("Generic CompareTo = {0}; non-generic CompareTo = {1}",
resultGeneric, resultNonGeneric);
}
}
}
/*
This example produces the following results:

The following is the result of using the generic and non-generic versions of the
CompareTo method for several base types:

Boolean:  True is equal to True
Byte:     1 is equal to 1
Int16:    -2 is less than 2
Int32:    3 is equal to 3
Int64:    4 is greater than -4
Decimal:  -5.5 is less than 5.5
Single:   6.6 is equal to 6.6
Double:   7.7 is greater than -7.7
Char:     A is equal to A
String:   abc is equal to abc
DateTime: 12/1/2003 5:37:46 PM is equal to 12/1/2003 5:37:46 PM
TimeSpan: 11.22:33:44 is equal to 11.22:33:44
Version:  1.2.333.4 is less than 2.0
Guid:     ca761232-ed42-11ce-bacd-00aa0057b223 is equal to ca761232-ed42-11ce-bacd-00
aa0057b223

The following types are not CLS-compliant:
SByte:    8 is equal to 8
UInt16:   9 is equal to 9
UInt32:   10 is equal to 10
UInt64:   11 is equal to 11
*/
```

Version Information

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0, 2.0, 1.0

Portable Class Library

Supported in: Portable Class Library
Supported in: Windows Phone 8.1
Supported in: Windows Phone Silverlight 8.1
Supported in: Windows Phone Silverlight 8